Two bad ways to make a door

[david s]

I tried AAC, it was 1" thick and it cracked. I tried the same idea a second time and exactly the same thing happened. Remember that the stuff is made from portland cement which doesn't like heat.

[Tscarborough]

I used mine 5 or 6 times and the heat certainly made the AAC even more brittle. The main problem though was that the heat caused the thinset to release.

[BackyardPermaculture]

They're really crumbly: i think you would want to totally enclose them.

"Really crumbly" is right - very hard to transport them without taking big chunks out of the corners.

[Tscarborough]

Just as an FYI when dealing with brittle/crumbly materials:

Round off all corners. You do not want any 90 degree intersections anywhere.

[BackyardPermaculture]

Thanks - sounds like useful advice.

[fornax hominus]

After burning up my previous door I was determined not to have it happen again [at least for a while]
I cut a cardboard template of the door opening and cut out an aluminum profile with 3 wings, bottom and sides , the top I cut a strip and angle braces and pop riveted it all together . on the hot face I put in a layer of ceramic board [1/2''] followed by aluminum foil and 3 '' of vermicrete topped by one more aluminum cut out . The facing is eastern white cedar and the handles are from a hickory maul handle [don't ask] . I dried it for a week on the back window ledge of my car [it was sunny] and I love It!

I am getting great heat retention and since there are no combustables near the inner face I can smother a raging fire! Sweet!
tim

[valtone1]

Hello,

Do you have any photos and more detailed step by step instructions along with a supply list you'd be willing to share ?

thanks Tony

[tmarsala]

Originally Posted by valtone1

Hello,

Do you have any photos and more detailed step by step instructions along with a supply list you'd be willing to share ?

thanks Tony

Hey, Tony. Good to hear from you!

Basically, I used birch plywood cut out in the shape of the main opening. Then from there I made a "plug" out of:layer 1) another piece of birch plywood the same size/shape as the vault opening, Layer 2) left over 2" Ceramic Fiber board that I got from Forno Bravo for under the hearth, the same size/shape as the vault opening, followed by Layer 3) a piece of 3/8 cement board the same size/shape as the vault opening. I used 2 1/2 inche deck screws through the cement board through the insulation directly into the plywood.

Around the plug I put a very small piece of fiberglass insulation and then around that a 4" "strap" of sheet metal all the way around the plug. So when I put the door in, the cement board faces the inside of the oven and the sheet metal is in contact with all of the brick around it. Watch your dimensions to make sure the door is snug, but not too tight. IT does loosen up after a few firings.

Here's the kicker that I found out from researching trying to make it fireproof: use a mixture of "Acryl 60" from your brick supplier (used to make mortar waterproof). it is a BASF product. Mix that with portland mortar into a very watery mixture and paint the whole door (except the sheet metal) with it. It turns out that the acrylic and the portland together soak into the wood, making it very UNcombustable. I have not had as much as a single char on my door and I put it in at 800+ degrees. From what I understand, this mixture (or some variant of it) has been used on fences in fire breaks to prevent them from burning or at least slowing down the combustion.

Sounds weird, but I was on my third door and I did not want to build another one, so I tried it with my leftover stuff (I used the acryl to make my outside brick render waterproof).


I will try to attach a picture, but I think my files are too big.

Let me know if you have any other questions!

Happy fire and bread!

Tom

[valtone1]

Tom,

Feel free to send photos to my e-mail address . valtone1@aol.com

Thanks again